This application claims priority from pending Korean Patent Application No. 2003-42839 filed on Jun. 27, 2003.
The present invention relates to a bumper system, and more particularly, to a bumper system that is designed to have a lightweight and a small volume while providing a high impact absorption performance, and that is designed to comprise individual components that can be replaced when they are damaged by impact, thereby reducing repairing cost.
Generally, a bumper is attached to either end of a vehicle to absorb impact in a collision, thereby protecting passengers. As shown in FIG. 1, a conventional bumper system comprises a bumper cover 1 defining an outer appearance of the bumper system, an energy absorber 2 formed of an elastic material such a polypropylene foam body or an urethane foam body to absorb impact energy, an impact beam for supporting the energy absorber 2, and a stay 4 for connecting the impact beam 3 to a vehicle body.
The impact beam has previously been formed of a steel material having a closed or xe2x80x9cCxe2x80x9d-shaped section. However, in recent years, to meet with a tendency toward more lightweight and compact vehicles, impact beams formed of a variety of materials have been developed. Particularly, as it has been proven that an impact beam formed of a glass mat thermoplastic (GMT) through a compression molding process is superior to other materials, it is widely employed to vehicles for export to North America where there are very strict regulations.
However, the conventional GMT-made impact beam is, as shown in FIG. 2, formed to be thick through its overall body to provide a necessary rigidity and strength. Therefore, the space saving and weight reducing effect is not so remarkable when compared with the steel beam. In addition, when tips are formed on an upper/lower end of the beam to improve the performance, the bumper cover and the energy absorber may be damaged by the tips in the case where the mounting space is not sufficient. Furthermore, although a reinforcing sheet has been applied to several conventional beams, since there is a need for an additional process for forming the reinforcing sheet, the manufacturing costs are increased.
Meanwhile, the energy absorber 2 is disposed between the bumper cover 1 and the impact beam 3 to absorb impact energy. When the energy absorber 2 is subject to an impact greater than its critical elastic force, it cracks and must therefore be replaced. However, in the conventional bumper system, since the energy absorber is integrally formed, the whole bumper system must be replaced, increasing the repairing costs.
Therefore, the present invention has been made in an effort to solve the problems of the related art.
An object of the present invention is to provide a bumper system that is designed to have a light weight and a small volume while providing a high impact absorption performance, and that is designed to comprise individual components that can be replaced when they are damaged by impact, thereby reducing repairing cost.
To achieve the object, the present invention provides a bumper system including a bumper cover; an energy absorber formed of a synthetic resin material through a foam molding process; an impact beam for supporting the energy absorber, the impact beam being formed of a glass mat thermoplastic and having a xe2x80x9cCxe2x80x9d-shaped section; and a stay for connecting the impact beam to a vehicle body, wherein tips are formed on front upper and lower portions of the impact beam, and a web portion is formed on the impact beam between the tips, and tip insertion grooves in which the tips are inserted are formed on an inner surface of the energy absorber, and a pressure receiving surface corresponding to the web portion is formed on the inner surface of the energy absorber.
According to the present invention, the impact beam is designed to maintain a sufficient rigidity and strength with a minimum thickness by increasing a sectional quadratic moment and a sectional coefficient by forming tips on the upper and lower portions thereof. In addition, since the web portion having a gentle curve is formed between the tips to support the energy absorber, a stress concentration phenomenon that may occur at a portion where the energy absorber contacts the tips can be prevented. As a result, a local crack that may occur at a portion where the energy absorber contacts the tips or a damage of the damper cover can be prevented.
Furthermore, because the high strength reinforcing sheet is formed on only a mid-portion of the impact beam in a lateral direction of the vehicle in the course of the compression molding process of the GMT, by being inserted in a mold for the impact beam, the strength of the impact beam can be effectively enhanced with minimum expenses.
In addition, since the energy absorber is divided into the central portion and the side portions, it is possible to replace only a damaged portion, thereby saving repairing costs. Furthermore, since the foam expansion of the central portion is less than those of the both sides, that is, since only the central portion is densely formed in the foam molding process, materials can be saved, reducing the weight of the energy absorber.